Course Description
During 2008, the National Geodetic Survey conducted an in-house study of the ability of the National Spatial Reference System to support the increasing demands for high accuracy positioning services and capabilities. One of the significant conclusions of that effort was that NAD 83 and NAVD 88 (and other island vertical datums) have sufficient deficiencies that will likely make them unable to support the potential for improved positioning technologies in the near future. To meet these challenges NGS has embarked on an effort to replace these datums with a more contemporary reference frame that will bring the United States geometric datum into closer alignment with the International Terrestrial Reference Frame and provide for a vertical datum based on gravity observations instead of geodetic leveling and the reliance on passive geodetic marks (i.e. bench marks). This class will discuss the rational for these changes, the on-going program of Gravity for the Redefinition of the American Vertical Datum (GRAV-D) and the changes in position and heights that will result from these new datums.
Learning Objectives
- Elements of the NGS 10 Year Plane
- Rational for updating the United States national datums
- Relationship between NAD 83 and ITRF
- Components of the GRAV-D program
- Potential changes in horizontal positions and heights
